The purpose of this study is to elucidate DA agonists and antagonists induced changes in pre- and postsynaptic DA neuronal systems. These studies will be focused on the following areas: 1) The mechanisms and activation of TH activity by c-AMP dependent protein kinase systems; 2. The regulation of tyrosine hydroxylase activity by specific DA receptors 3. The purification of enzymes involved in monoamine biosynthesis. The properties of these enzymes will be characterized and purified enzymes will be utilized for production of specific antisera. 4. The biochemical and morphological interaction of the Epinephrine neuronal systems with other monoaminergic systems will be studied. 5. Methods will be developed for characterization and purification of multiple DA receptors. 6. The effect of chronic treatment with DA agonists and antagonists on pre- postsynaptic neuronal systems will be investigated. We hope that the results of our study will provide new insight on biochemical changes which occur during treatments of mental and neurological disorders with DA antagonists and agonists.